A motion-vector detector determines the centroid of pixels on a reference frame that is identified with position information set in a database and associated with a feature address corresponding to a feature of a target pixel. The motion-vector detector detects, as a motion vector of the target pixel, a vector that has a starting point at a pixel on the reference frame which corresponds to the target pixel on a current frame and has an end point at the determined centroid. The present invention can be applied to an apparatus for generating a motion vector and allows prompt detection of a motion vector.